Smaller engine compartments have restricted the available space for mounting accessory devices and systems. In particular it has been a problem to provide enough space to disconnect and connect screw fittings for joining tube segments of a refrigerant system used in vehicular air conditioning. Such screw fittings require use of wrenches to turn the fittings for fastening them together and for disconnecting them to make necessary repairs. The use of wrenches requires a radius turning space that is not always available.
Another problem with such fittings is that the system is often under pressure which is relieved when the tube couplings are broken.
Prior art couplings are known which can be connected by manual insertion and rotation so as to interconnect the tube portions by use of lug ears such as are shown in U.S. Pat. Nos. 1,221,935; 1,232,193; 1,274,406; 1,430,558; and 2,265,267. These couplings, however, do not provide for interlock mechanism which can be visually aligned from the outside of the coupling components. Furthermore, such couplings do not provide for a control collar with a cam surface which will align a relief port on one of the tubes to relieve pressure in the connected tube portions before they are fully separated.
Other prior art couplings have a cam groove on a tube which will receive a tab on another tube for joining the tubes together when the tubes are relatively rotated while applying a connecting force so as to cause the tabs to track within the cam slot to an offset interlock position therein. While suitable for their intended purpose such couplings, they do not provide a cam slot configured to provide a relief surface which will locate a relief port on one of the tubes to relieve pressure in the connected tube portions before they are fully separated. Examples of such couplings include U.S. Pat. Nos. 1,657,488; 1,744,367; 1,938,571; 4,632,433 and 4,909,545.